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1. Particle Size and Rheology of Silica Particle Networks at the Air–Water Interface

   https://doi.org/10.3390/nano13142114  

   Thakur, Siddharth; Razavi, Sepideh (July 2023, Nanomaterials)

   Silica nanoparticles find utility in different roles within the commercial domain. They are either employed in bulk within pharmaceutical formulations or at interfaces in anti-coalescing agents. Thus, studying the particle attributes contributing to the characteristics of silica particle-laden interfaces is of interest. The present work highlights the impact of particle size (i.e., 250 nm vs. 1000 nm) on the rheological properties of interfacial networks formed by hydrophobically modified silica nanoparticles at the air–water interface. The particle surface properties were examined using mobility measurements, Langmuir trough studies, and interfacial rheology techniques. Optical microscopy imaging along with Langmuir trough studies revealed the microstructure associated with various surface pressures and corresponding surface coverages (ϕ). The 1000 nm silica particle networks gave rise to a higher surface pressure at the same coverage compared to 250 nm particles on account of the stronger attractive capillary interactions. Interfacial rheological characterization revealed that networks with 1000 nm particles possess higher surface modulus and yield stress in comparison to the network obtained with 250 nm particles at the same surface pressure. These findings highlight the effect of particle size on the rheological characteristics of particle-laden interfaces, which is of importance in determining the stability and flow response of formulations comprising particle-stabilized emulsions and foams. 

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2. Particle Size-Dependent Electrophoresis in Polymer Solutions

   https://doi.org/10.1021/acs.analchem.3c05655  

   Bentor, Joseph; Xuan, Xiangchun (February 2024, Analytical Chemistry)
3. On-Site Particle Size Distribution by FieldSed

   https://doi.org/10.1061/9780784482131.015  

   Ventola, A. and (January 2019, Proceedings of GeoCongress)

   null (Ed.)

   A previously-developed SedImaging test quickly determines the particle size distribution (PSD) of coarse-grained soils. The test involves photographing and analyzing a soil following sedimentation through water to sort its particles by size. Generating a PSD by SedImaging takes a fraction of the time required by traditional sieving. Due to its large size and weight, the original SedImaging device is suitable only for laboratory settings. Therefore, a new FieldSed system has been designed as a field-adaptable version of the original SedImaging system. While it utilizes the same Harr wavelet image analysis methods as the original SedImaging test, FieldSed uses smaller-scale, lightweight hardware to make it practical for use in any testing environment. FieldSed also enables many parallel tests to be performed, thus greatly reducing testing time. The FieldSed-produced PSDs match sieving results very well. 

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4. Dependence of Nonlinear Electrophoresis on Particle Size and Electrical Charge

   https://doi.org/10.1021/acs.analchem.2c05595  

   Ernst, Olivia D.; Vaghef-Koodehi, Alaleh; Dillis, Curran; Lomeli-Martin, Adrian; Lapizco-Encinas, Blanca H. (April 2023, Analytical Chemistry)
5. Quantitative microbial taxonomy across particle size, depth, and oxygen concentration

   https://doi.org/10.3389/fmicb.2025.1552305  

   Huanca-Valenzuela, Paulina; Fuchsman, Clara A; Tully, Benjamin J; Sylvan, Jason B; Cram, Jacob A (May 2025, Frontiers in Microbiology)

   Srivastava, Abhishek (Ed.)

   IntroductionMarine particles form in the ocean surface sink through the water column into the deep ocean, sequestering carbon. Microorganisms inhabit and consume carbon in these particles. The East Pacific Rise (EPR) harbors both an Oxygen Deficient Zone (ODZ) and a non-buoyant plume region formed from hydrothermal vents located on the ocean floor, allowing us to explore relationships between microbial community and particle size between a range of environments. MethodsIn this study, we quantified microbial diversity using a fractionation method that separated particles into seven fine scale fractions (0.2–1.2, 1.2–5, 5–20, 20–53, 53–180,180–500, >500 μm), and included a spike-in standard for sequencing the 16S rRNA gene. Size fractionated organic carbon into the same fractions enabled the calculation of bacterial 16S rRNA copies per μg C and per liter. ResultsThere was a large increase in the bacterial 16S rRNA copies/ug C and copies/L on particles >180 μm between the upper water column and the deep water column. Though the total concentration of organic C in particles decreased in the deep water column, the density of bacteria on large particles increased at depth. The microbial community varied statistically significantly as a function of particle size and depth. Quantitative abundance estimates found that ostensibly obligate free-living microbes, such as SAR11 and Thaumarcheota, were more abundant in the free-living fraction but also common and abundant in the particulate size fractions. Conversely, ostensibly obligate particle attached bacteria such as members of Bacteroidetes and Planctomycetes, while most abundant on particles, were also present in the free living fraction. Total bacterial abundance, and the abundance of many taxonomic groups, increased in the ODZ region, particularly in the free-living fraction. Contrastingly, in the non-buoyant plume, there were highly abundant bacteria in the 5–20 and 20–53 μm fractions but reduced bacteria present in the 53–180 and 180–500 μm fractions. ConclusionQuantitative examination of microbial communities highlights the distribution of microbial taxa unburdened by compositional effects. These data are congruent with existing models which suggest high levels of exchange between particle-attached and free-living communities. 

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